Air or gas circulation rock bit anticontamination valve



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v C/FU ,/U i E A W z a@ Aug. 23, 1966 AIR OR GAS CIRCULATION ROCK BIT ANTI-CONTAMINATION VALVE United States Patent O 3,268,018 AIR R GAS CIRCULATION ROCK BIT ANTI- CONTAMINATION VALVE William J. Neilson, Whittier, Calif., assignor to Smith Tool Co., Compton, Calif., a corporation of California Filed Oct. 14, 1963, Ser. No. 316,064 3 Claims. (Cl. 175-318) This invention relates to improvements in rock bits employed in drilling wells. The conventional rock bit consists of a body attachable t-o the lower end of a drill string which body has downwardly extending legs on which there are journals that rotatably mount roller cutters. The :body usually has a central circulation uid passage therethrough through which a liquid circulation uid such -as mud is discharged for the purpose of cooling and cleaning the cutters and iiushing the cuttings upwardly through the well bore.

For various reasons many wells are now being drilled which, instead of employing a liquid circulation fluid, employ either a compressed gas or compressed air. Such circulation fluids -are forced downthe drill string and are discharged through the body of the bit and flush the cuttings upwardly in the well bore. In order to cool the antifriction bearings that rotatably mount the roller cutters on the journals the body is equipped with branch passages that communicate with the circulation fluid passage in the body. These branch passages conduct a portion of the circulation fluid--in this instance, air or gas-to the interiors of the roller cutters. The air or gas is thus forced rapidly through the anti-friction bearings and escapes from the cutters adjacent the inner sides of the legs on which the cutters are rotatably mounted. The continuous tiow of the air or gas throu-gh the bearings serves to cool them sufficiently to assure continued rotation of the cutters as the drill string and body are rotated and prevents ingress of abrasive cuttings into the bearings.

It is sometimes desirable to introduce a small amount of water into the air or gas at the top of the drill string so that it will be carried down the drill str-ing in the form of water vapor. However whether or not water is introduced into the air or gas before it is pumped down the drill string, water strata are frequently encountered in the course of drilling the well. Consequently for either or both of these reasons moisture may be present in or around the bit while the well is being drilled using gaseous circulation fluids. Because of the presence of moisture, when drilling operations are temporarily halted, such as is occasioned by the addition of another stand of drill pipe to the drill string, a reversal of flow of the gaseous circulation iluid and moisture may take place. This is apt to cause moistened rock dust or cuttings to be carried upwardly into the body of the bit and to settle in and plug the branch passages that conduct circulation fluid to the bearings of the cutters. If one or more of the branch passages become thus plugged, their respective cutters are consequently deprived of circulation uid when drilling operations are resumed. The bearings in the cutters heat rapidly and may freeze so that the cutter no longer rotates on its journal. This results in a rapid destruction of the cutter requiring that the drill string and bit be removed and the bit replaced.

It is a primary object of the` present invention to provide a novel rock bit for drilling with gaseous circulation fluids wherein a one-way valve means is located in the circulation passage through the body of the bit below the points of communication of the branch passages therewith. This one-way valve means permits of the downward ow of the gaseous circulation uid during normal drilling operations but prevents reverse iiow therethrough. Consequently when drilling operations are temporarily suspended and there might be a tendency for reverse flow 3,268,018 Patented August 23, 1966 ICC to take place, moistened powders or cuttings cannot enter the circulation fluid passage, settle or collect in the branch passages, and plug them.

Another object of the invention is to provide a well drilling bit having the above mentioned characteristics wherein a one-Way valve means is readily removable and may be easily substituted for. The one-way valve means has passages therethrough which, in effect, throttle or regulate the amount of gaseous circulation fluid that is discharged by the body of the bit against or between the cutters. As the drilling of the well proceeds there frequently is occasion to vary or chan-ge the amount of circulation fluid that is discharged. This variation can be readily accomplished by removing the one-way valve means and substituting another having different sizes of passages therethrough.

With the foregoing and other objects in view, which will be made manifest inthe following detailed descrip-tion and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

FIGURE 1 is a partial view in vertical section through a well drilling bit embodying the present invention.

FIG. 2 is a partial view in horizontal sect-ion taken substantially upon the line 2 2 upon FIG. 1 in the direction indicated.

Referring to the -accompanying drawing wherein similar reference characters designate similar parts throughout, the bit embodying the presen-t invention consists of a body generally indicated at 10' conventionally having at its top a threaded pin 11 by which it may be attached to the lower end of a drill string. The body has downwardly extending legs 12 only one of which is shown but it may be understood that there are usually three or four of such legs. Each of the legs has an inwardly extending journal 13 that is usually integral therewith and on each journal there is rotatably mounted a roller cutter y14. Usually anti-friction bearings (not shown) are interposed between the cutter 14 and the journal 13. These frequently are both roller bearings and ball bearings, the ball bearings being inserted between their races on the interior of the cutter and on the exterior of the journal through an opening 15 that is subsequently closed .by a ball plug 16 welded in place such as by a weld 17. The ball plug 16 has a portion which is of reduced diameter indicated at 18 that provides a clearance space leading around the ball plug to the ball bear-ing of the anti-friction bearings. This clearance space, indicated at 19, communicates with a branch passage 20 in each leg 12 and the branch passages 20 in turn communicate at their upper ends with a Vertical central circulation passage 21 in the body of the bit. ln the course of drilling the gaseous circulation fiuid which may be moistened is forced down the drill string and is discharged through the passage 21 against or between the .roller cutters 14. A portion of the circulation fluid is forced through tbe branch passages 20 and through the clearance space 19 to the interior of the roller cutters 14, where it passes between the balls or rollers of the antifriction bearings and iinds egress through the clearance space 22. This portion of the circulation iluid discharging continuously in this manner serves to cool the anti-friction bearings and prevents ingress of abrasive cuttings to the bearings.

In accordance with the present invention, a shoulder 23 that faces upwardly is formed in the circula-tion fluid passage 21. This shoulder serves to support a perforated plate 24 in which a plurality of discharge ports 25 a-re formed. As illustrated, the number of discharge ports 25 is shown as bei-ng three, but their number and their sizes may vary. On the underside of the plate 24 there is secured a section of flexible material 26 which may be of leather, neoprene rubber or the like. This section is divided by Iradial slots 27 -into lobes 28 all of which are centrally connected to each other around the attaching bolt 29. The lobes function as apper valves and serve as oneeway check valves which permit of downward ow of circulation fluid through the ports 25 during normal drilling operations. However when drilling is temporarily halted or suspended and there is any occasion for reverse flow, the lobes 28 prevent upward flow through the passage 21. As this one-way valve means is located below the points of communication of the branch passages 20 Wit-h the circulation uid passage 21, .no dust or cuttings can -rise in the circulation passage 21, settle or co1- lect in the branch passages 20, and plug these passages such as is apt to occur particularly when the gaseous circulation fluid has been moistened.

The plate 24 and its attached ilexible lobes 28 is retained in place against the shoulder 23 by a tubular sleeve 30 that lits snugly Within the circulation fluid passage 21 below the points of communication of the branch pass-ages 20 therewith. Adjacent the points of communication of the branch passages 20 with the circulation ll-uid passage this sleeve isi-n spaced relation to the Walls of the circulation iluid passage 21. The top of the sleeve 30 is flared and divided into outwardly extending lingers 31 which are engaged by and retained in place such as by a split snap ring 32.

As drilling operati-ons proceed there may be occasion to alter or vary the size or shape of the ports 25 in the plate 24. This can be readily accomplis-hed by removal of the snap ring 312, 'withdrawing the sleeve 30, and substituting a different plate 24 having the desired or required size and shape of ports 25.

From the above described construction it will be alppreciated that an improved rock bit has been developed primarily designed for use with gaseous circulation fluids. In such bits a portion of the circulation uid is conducted to the interior ot each roller cutter and discharged through its anti-friction hearings to cool them. Provision is made for preventing reverse iow of circulation uid and cuttings through the bit which might tend to plug the branch passages `)whenever drilling operations are temporarily suspended. The one-way va-lve means used Yfor this purpose is readily removable and replaceable to vary the amount of circulation lluid that is discharged by the body against or between the cutters.

Various changes may be made in the details of the cnstruction without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. A rock bit having a body on which cutters are rotatably mounted, said body having a main circulation passage therethrough for the discharge of circulation Huid,

|and having branch passages each with a point of communication with the main circulation passage and leading to the interiors of the cutters, an imperforate tubular sleeve having its lower end snugly fitting the main circulation passage below the points of communication of the branch passages therewith, said sleeve extending above said points of communication, the wall of said main circulation passage adjacent the upper end of said sleeve being spaced outwardly from said sleeve to provide circulation in the main passage eXteriorly of the sleeve to said points of communication with said branch passages as well as interiorly of the sleeve, releasable sleeve anchoring means engaging the wall of said passage and said sleeve, and a substitutable downwardly opening one-Way valve supported in and upward-ly removable from said main circulation passage and held in position beneath and by said sleeve.

2. A rock bit having a body on which cutters are rotatably mounted, said body having a main circulation passage downwardly therethrough for the discharge of circulation duid and having branch passages, the latter having points of communication with the main circulation passa-ge and leading to the interiors of the cutters, said main passage having a support therein belotw said points of communication of the lbranch passages, an apertured orifice plate resting upon said support, a one-way upwardly closing val-ve element and supporting means therefor adjacent said orifice plate, a sleeve in said main circulation passage having its lower end snugly tting said main passage and resting upon sai-d orifice plate, said sleeve eX- tending above said points of communication, the Wall of said main circulation passage adjacent the upper end of said sleeve being spaced outwardly from said sleeve to p-rovide circulation in the main passage exteriorly of the sleeve to said points of communication with said branch passages as well as interiorly of the sleeve, and releasable means in said main passage engaging the upper end of said retainer sleeve to hold said sleeve' and orice plate in position in said main passage.

3. The structure in claim 2 and said retainer sleeve, from its bottom to a point albcve said points of commu-nication of said branch passa-ges having a wall portion free of apertures.

Reerences Cited by the Examiner UNlTED STATES PATENTS 1,191,628 7/1916 Thin-ks 137-525 1,342,216 6/ 1920' Henig 137-525 3,198,269 9/ 1965 Nickles 175-337 CHARLES E. OCONNELL, Primary Examiner.

J. A. LEPPINK, Assistant Examiner. 

1. A ROCK BIT HAVING A BODY ON WHICH CUTTERS ARE ROTATABLY MOUNTED, SAID BODY HAVING A MAIN CIRCULATION PASSAGE THERETHROUGH FOR THE DISCHARGE OF CIRCULATION FLUID, AND HAVING BRANCH PASSAGES EACH WITH A POINT OF COMMUNICATION WITH THE MAIN CIRCULATION PASSAGE AND LEADING TO THE INTERIORS OF THE CUTTERS, AN IMPERFORATE TUBULAR SLEEVE HAVING ITS LOWER END SNUGLY FITTING THE MAIN CIRCULATION PASSAGE BELOW THE POINTS OF COMMUNICATION OF THE BRANCH PASSAGES THEREWITH, SAID SLEEVE EXTENDING ABOVE SAID POINTS OF COMMUNICATION, THE WALL OF SAID MAIN CIRCULATION PASSAGE ADJACENT THE UPPER END OF SAID SLEEVE BEING SPACED OUTWARDLY FROM SAID SLEEVE TO PROVIDE CIRCULATION IN THE MAIN PASSAGE EXTERIORLY OF THE SLEEVE TO SAID POINTS COMMUNICATION WITH THE BRANCH PASSAGES AS WELL AS INTERIORLY OF THE SLEEVE, RELEASABLE SLEEVE ANCHORING MEANS ENGAGING THE WALL OF SAID PASSAGE AND SAID SLEEVE, AND A SUBSTITUTABLE DOWNWARDLY OPENING ONE-WAY VALVE SUPPORTED IN AND UPWARDLY REMOVABLE FROM SAID MAIN CIRCULATION PASSAGE AND HELD IN POSITION BENEATH AND BY SAID SLEEVE. 